X-ray FEL with a meV bandwidth

Saldin, Evgeni; Schneidmiller, E.A.; Shvyd’ko, Yu. V.; Yurkov, M.V.

doi:10.1016/s0168-9002(01)01539-x

Cited by 108 publications

(97 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These methods, which include High Gain Harmonic Generation (HGHG) [15][16][17][18] and Echo-Enabled Harmonic Generation (EEHG) [19,20], rely on a synchronised external seed at the appropriate wavelength, pulse energy and repetition rate. In the second class, the coherence is created by optical manipulation of the FEL radiation itself, for example by spectrally filtering the SASE emission at an early stage for subsequent re-amplification to saturation in a self-seeding method [21][22][23][24], or via the use of an optical cavity [25][26][27][28][29][30][31][32]. Methods in this class rely on potentially complex material-dependent optical systems which limit the ease and range of wavelength tuning.…”

mentioning

confidence: 99%

Transform-Limited X-Ray Pulse Generation from a High-Brightness Self-Amplified Spontaneous-Emission Free-Electron Laser

2013

View full text Add to dashboard Cite

A method to achieve High-Brightness Self-Amplified Spontaneous Emission (HB-SASE) in the Free Electron Laser (FEL) is described. The method uses repeated non-equal electron beam delays to de-localise the collective FEL interaction and break the radiation coherence length dependence on the FEL cooperation length. The method requires no external seeding or photon optics and so is applicable at any wavelength or repetition rate. It is demonstrated using linear theory and numerical simulations that the radiation coherence length can be increased by approximately two orders of magnitude over SASE with a corresponding increase in spectral brightness. Examples are shown of HB-SASE generating transform-limited FEL pulses in the soft X-ray and near transform-limited pulses in the hard X-ray. Such pulses may greatly benefit existing applications and may also open up new areas of scientific research.In the X-Ray region of the spectrum Self-Amplified Spontaneous Emission (SASE) free-electron lasers (FELs) are currently opening up new frontiers across science [1][2][3][4][5][6]. Although SASE FELs have brightness up to 10 8 times greater than laboratory sources their full potential is limited by a relatively poor temporal coherence. In this Letter, a High Brightness SASE (HB-SASE) FEL is described which may significantly improve the temporal coherence towards the transform limit, enhancing the spectral brightness and potentially enabling X-ray FELs to enhance their existing scientific capability and to access new experimental regimes.Applications that may benefit include Resonant Inelastic X-ray Scattering (RIXS) [7] which requires substantial incident photon flux to collect sufficient spectra with a high enough resolution in energy and momentum in a reasonable time. RIXS has evolved greatly over the last decades, due to increases in photon flux from synchrotron sources then X-ray FELs, as well as advances in instrumentation. Each increase in resolution has revealed new details in material excitation spectra. Further improvement may extend study to e.g. single magnons in small exchange systems and the full dispersion curves of superconducting gaps. New applications made possible by fourier-transform limited X-ray pulses may include time-resolved X-ray spectroscopy of chemical dynamics, or quantitative studies of molecular and cluster fragmentation, where high repetition rate pulses of controlled temporal profile are essential for systematic studies of nonlinear phenomena [8].In the SASE FEL [9, 10], a relativistic bunch of electrons with a Lorentz factor of γ ≫ 1 enters an undulator comprising an array of transverse, alternating polarity dipole magnets of period λ u . The undulator magnetic fields cause the electrons to oscillate transversely and emit initially incoherent radiation. A cooperative (or collective) instability in the coupled electron-radiation system may cause an exponential gain in the radiation field and an electron microbuncing at the resonant radiation wavelength λ r = λ u (1 +ā2 , whereā u is the rms undul...

show abstract

mentioning

confidence: 99%

Transform-Limited X-Ray Pulse Generation from a High-Brightness Self-Amplified Spontaneous-Emission Free-Electron Laser

2013

View full text Add to dashboard Cite

show abstract

“…durations varying between about 1 fs and 15 fs for the radiation wavelength of 0.1 nm and between 20 fs and 40 fs for 1 nm wavelengths. Some of the simulations were carried out with the standard SASE (Kondratenko & Saldin, 1980;Bonifacio et al, 1984) configuration, whereas some others include the option of self-seeding (Feldhaus et al, 1997;Saldin et al, 2001;Geloni et al, 2010;Amann et al, 2012) to reduce the bandwidth of the FEL pulse. Fig.…”

Section: Simulation Of Fel Pulsesmentioning

confidence: 99%

Simulation of FEL pulse length calculation with THz streaking method

Gorgisyan

Ischebeck

Prat

et al. 2016

J Synchrotron Radiat

View full text Add to dashboard Cite

Having accurate and comprehensive photon diagnostics for the X-ray pulses delivered by free-electron laser (FEL) facilities is of utmost importance. Along with various parameters of the photon beam (such as photon energy, beam intensity, etc.), the pulse length measurements are particularly useful both for the machine operators to measure the beam parameters and monitor the stability of the machine performance, and for the users carrying out pumpprobe experiments at such facilities to better understand their measurement results. One of the most promising pulse length measurement techniques used for photon diagnostics is the THz streak camera which is capable of simultaneously measuring the lengths of the photon pulses and their arrival times with respect to the pump laser. This work presents simulations of a THz streak camera performance. The simulation procedure utilizes FEL pulses with two different photon energies in hard and soft X-ray regions, respectively. It recreates the energy spectra of the photoelectrons produced by the photon pulses and streaks them by a single-cycle THz pulse. Following the pulseretrieval procedure of the THz streak camera, the lengths were calculated from the streaked spectra. To validate the pulse length calculation procedure, the precision and the accuracy of the method were estimated for streaking configuration corresponding to previously performed experiments. The obtained results show that for the discussed setup the method is capable of measuring FEL pulses with about a femtosecond accuracy and precision.

show abstract

“…The natural bandwidth of the SASE-XFEL pulses is of the order of the Pierce parameter (Bonifacio et al, 1984), with values between 10 À3 and 10 À4 for a typical XFEL facility. To improve the longitudinal coherence of SASE-XFELs, seeding techniques are employed, which further reduce the radiation bandwidth close to the Fourier limit (Feldhaus et al, 1997;Saldin et al, 2001;Geloni & Saldin, 2010;Amann et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Generation of ultra-large-bandwidth X-ray free-electron-laser pulses with a transverse-gradient undulator

Prat

Calvi

Reiche

2016

J Synchrotron Radiat

View full text Add to dashboard Cite

A new and simple method to generate X-ray free-electron-laser radiation with unprecedented spectral bandwidth above the 10% level is presented. The broad bandwidth is achieved by sending a transversely tilted beam through a transverse-gradient undulator. The extent of the bandwidth can easily be controlled by variation of the beam tilt or the undulator gradient. Numerical simulations confirm the validity and feasibility of this method.

show abstract

X-ray FEL with a meV bandwidth

Cited by 108 publications

References 16 publications

Transform-Limited X-Ray Pulse Generation from a High-Brightness Self-Amplified Spontaneous-Emission Free-Electron Laser

Transform-Limited X-Ray Pulse Generation from a High-Brightness Self-Amplified Spontaneous-Emission Free-Electron Laser

Simulation of FEL pulse length calculation with THz streaking method

Generation of ultra-large-bandwidth X-ray free-electron-laser pulses with a transverse-gradient undulator

Contact Info

Product

Resources

About